[ Java 代碼範本 ] Get All Classes Within A Package

Source From Here 
Preface 
The code below gets all classes within a given package. Notice that it should only work for classes found locally, getting really ALL classes is impossible. 

Sample Code 
Consider the project has below package hierarchy: 
 

Try below sample code: 
- test.Test.java 

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1. package test;  
2.   
3. import java.io.File;  
4. import java.io.IOException;  
5. import java.net.URL;  
6. import java.util.ArrayList;  
7. import java.util.Enumeration;  
8. import java.util.List;  
9.   
10. public class Test {  
11.     public static class A{  
12.         String name;  
13.     }  
14.       
15.     /** 
16.      * Scans all classes accessible from the context class loader which belong to the given package and subpackages. 
17.      * 
18.      * @param packageName The base package 
19.      * @return The classes 
20.      * @throws ClassNotFoundException 
21.      * @throws IOException 
22.      */  
23.     private static List GetClasses(String packageName)  
24.             throws ClassNotFoundException, IOException {  
25.         ClassLoader classLoader = Thread.currentThread().getContextClassLoader();  
26.         assert classLoader != null;  
27.         String path = packageName.replace('.', '/');  
28.         Enumeration resources = classLoader.getResources(path);  
29.         List dirs = new ArrayList();  
30.         while (resources.hasMoreElements()) {  
31.             URL resource = resources.nextElement();  
32.             dirs.add(new File(resource.getFile()));  
33.         }  
34.         ArrayList classes = new ArrayList();  
35.         for (File directory : dirs) {  
36.             classes.addAll(FindClasses(directory, packageName));  
37.         }  
38.         return classes;  
39.     }  
40.   
41.     /** 
42.      * Recursive method used to find all classes in a given directory and subdirs. 
43.      * 
44.      * @param directory   The base directory 
45.      * @param packageName The package name for classes found inside the base directory 
46.      * @return The classes 
47.      * @throws ClassNotFoundException 
48.      */  
49.     private static List FindClasses(File directory, String packageName) throws ClassNotFoundException {  
50.         List classes = new ArrayList();  
51.         if (!directory.exists()) {  
52.             return classes;  
53.         }  
54.         File[] files = directory.listFiles();  
55.         for (File file : files) {  
56.             if (file.isDirectory()) {  
57.                 assert !file.getName().contains(".");  
58.                 classes.addAll(FindClasses(file, packageName + "." + file.getName()));  
59.             } else if (file.getName().endsWith(".class")) {  
60.                 classes.add(Class.forName(packageName + '.' + file.getName().substring(0, file.getName().length() - 6)));  
61.             }  
62.         }  
63.         return classes;  
64.     }  
65.       
66.     public static void main(String args[]) throws Exception  
67.     {  
68.         String pkg = "test";  
69.         System.out.printf("\t[Info] Search package: %s\n", pkg);          
70.         for(Class clz:GetClasses(pkg))  
71.         {  
72.             System.out.printf("\t%s\n", clz.getName());  
73.         }  
74.     }  
75. }  

Execution result: 

[Info] Search package: test
test.abc.C
test.B
test.Test$A
test.Test